The objective of this project is to define the regulatory mechanisms that control the program of gene transcription during the differentiation of bacteria into dormant spores. Overlapping DNA segments from the spore-forming bacterium Bacillus subtilis have been cloned that contain several of the most actively transcribed genes of the sporulation process. These genes are clustered within a 10 kilobase segment of the chromosome and are activated at different stages of spore development. Experiments are proposed to determine the location of this gene cluster on the B. subtilis genetic map and to identify the protein products that these genes encode. Our ultimate goal is to employ cloned DNAs as templates for reconstructing in vitro specific transcription of individual genes under sporulation control. In pilot experiments we have identified a modifed form of core RNA polymerase that selectively and asymmetrically copies a gene that is activated at an early stage of spore development.